1. Field of the Invention
The present invention is directed to soft quaternary surface active agents and more specifically, to soft quaternary surface active agents characterized as being substantially antibacterial in nature but of low toxicity due to their ability to degrade into relatively nontoxic, nonquaternary by-products subsequent to exerting their antibacterial activity.
2. Description of the Prior Art
One of the basic methods of synthesis of the compounds encompassed within the above-described generic formula consists in reacting a compound of the formula (A) below wherein R and R.sub.1 are defined as above with a compound of the formula (B) below, wherein R, R.sub.1, ##STR7## and X are defined as above: ##STR8##
A few of the compounds of formula (A) above are old in the art and are formed by the reaction between an aldehydr (R--CHO) and an acyl halide ##STR9## See, R. Adams and E. H. Vollweiler, J. Amer. Chem. Soc., 40, 1732 (1918); H. E. French and R. Adams, ibid., 43, 651 (1921); L. H. Ulich and R. Adams, ibid., 43, 660 (1921).
Thus, preparation of the compounds of formula (A) can be described by reference to the following equation, wherein R and R.sub.1 are defined as above: ##STR10## An alternate method of preparing the compounds of formula (A) resides in reacting a salt of the acid R.sub.1 -COOH with a nonsymmetric dihalo derivative ##STR11## as follows: ##STR12## using an inert solvent such as dimethylformamide at or below room temperature.
The compounds of formula (A) have been used in the past to protect a carboxy function in the following manner: ##STR13##
In the above equation, R and R.sub.1 are defined as above; R.sub.2 represents the residue of ampicillin or a salicylic acid derivative; and M represents an alkali metal salt (Na, K, etc.). See, "Acyloxymethyl Esters of Ampicillin," W. V. Daehne, E. Fredricksen, E. Gundersen, F. Lund, P. Morch, H. J. Petersen, K. Roholt, L. Tybring, and W. V. Godfredsen, J. Med. Chem., 13, 607 (1970), or British Pat. No. 1,220,457. While those compounds of formula (A) have been used as outlined above, i.e., protecting the carboxy function, this utility has no bearing on the invention disclosed and claimed herein. On the other hand, it is generally known that any activated haloalkyl compound (e.g., benzyl bromide or chloride) will react with a tertiary aliphatic amine to form the corresponding quaternary ammonium salt. However, this salt does not undergo hydrolytic cleavage, which is a necessary characteristic of the labile quaternary ammonium salts of this invention.
"Hard" quaternary salt surface active agents are known and widely used for numerous purposes in cosmetics, cleansing preparations and antimicrobial preparations, e.g., mouthwashes, shampoos, soaps, etc. These quaternary salts which are a very short chain length are highly toxic whereas those of long chain length are less toxic but only due to their inability to be readily absorbed. For instance, the LD.sub.50 for cetylpyridinium chloride via oral versus I.P. administration is substantially greater. See Example III, infra.
In addition, it is now believed that such "hard" quaternary salt surface active agents, which alter surface tension in the liver, do, in fact, influence a number of chemical and physical processes in the liver. Consequently, such agents have an indirect toxic effect on the hepatic system.
Accordingly, a need arises for a "soft" surface active agent which, subsequent to exerting its desired effect, will "cleave" via chemical and/or enzymatic hydrolysis to release nontoxic and nonsurface active moieties. That is, it is desirable to develop a quaternary derivative which, after exerting its desired effect, will "cleave" via chemical and/or enzymatic hydrolysis to release nonquaternary, nontoxic by-products.
U.S. Patent Application, Ser. No. 482,513--Bodor discloses similar compounds having little, if any, antibacterial activity. This application was filed on June 24, 1974 and has since been allowed.